Hi, I'm running into an issue with performance measurements on an iSCSI volume. The volume has set a QoS value of max. 30.000 iops. I run tests with the libaio engine against the volume with the following base parameter: fio --filename=/dev/sde --ioengine=libaio --direct=1 --buffered=0 --atomic=1 --bs=4k --invalidate=0 --readwrite=[read,write,randwrite,randread] --iodepth=128 --time_based --runtime=1200 --name=ft --write_iops_log=w_iops_log --write_bw_log=w_bw_log --write_lat_log=w_lat_log --output=fio_log With randread/randwrite everything is as expected. The volume reaches the QoS max value and not more. But with write/read/readwrite I can get over the max QoS IOPs: ~41k iops. After some investigation with wireshark it seems with seq r/w packages are aggregated (e.g. 8k TCP packages instead of 4k), which they are not with randwrite. Is there an issue in libaio or in fio? Or is it an expected behavior from the kernel? Danny -- To unsubscribe from this list: send the line "unsubscribe fio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
